Antibiotic use enhances the growth of healthy domesticated poultry and livestock. Although extensive bans and restrictions have not been implemented in the United States as they have in the E.U. and other countries, pressure for antibiotics alternatives has increased due to concerns of increasing antibiotic resistance among food borne bacteria. Banning or markedly reducing the agricultural and farm-veterinary use of antibiotics may have a profound negative impact on the safety of foods and on the treatment of sick flocks or herds of domesticated livestock, however. Thus, effective, safe and environmentally friendly alternative(s) to antibiotics are needed to address these concerns and needs.
Viruses that kill bacteria were first identified in the early part of the 20th century by Frederick Twort and Felix d'Herelle who called them bacteriophages or bacteria-eaters (from the Greek phago meaning to eat or devour). Because of their remarkable antibacterial activity, phages were used to treat disease of economically important animals/domesticated livestock almost immediately after their discovery, and therapeutic applications for humans closely followed. However, with the advent of antibiotics, phage therapy gradually fell out-of-favor in the United States and Western Europe, and virtually no subsequent research was done on the potential therapeutic application of phages for bacterial diseases of humans or animals. The emergence of antibiotic-resistance in bacteria, however, has rekindled interest in therapeutic bacteriophages. Phage therapy may have a positive impact on human health by improving the safety of foods in the U.S.A. and elsewhere, and by helping to reduce safely the use of antibiotics in agribusiness.
Among the bacteria that cause significant morbidity and mortality in chickens, C. perfringens is one of the most notorious pathogens. In chicken C. perfringens infections are often manifested as necrotic enteritis that occur later in the production cycle, often following a coccidial infection or other insult to the gastrointestinal tract. It is thus desirable to develop bacteriophage preparations suitable to reduce morbidity and mortality in chickens.
C. septicum is an anaerobic bacterium which causes or contributes to gas gangrene and malignant edema in animals and people, usually following direct contact of a traumatic wound. C. septicum multiplies locally and disseminates throughout the animal's body, producing local lesions and signs of toxemia (Songer, 1996). Specifically for turkeys and chickens, C. septicum is implicated in gangrenous dermatitis (or cellulitis), an economically important disease (Tellez et al., 2009; NTF, 2007). Typically, antibiotics are used to treat or prevent C. septicum infections in poultry (Songer, 1996, NTF, 2007).
Clostridium difficile is well established as a pathogen of horses, calves, and pigs, as well as poultry. Clostridium difficile is a normal inhabitant of the gastrointestinal tract of many species of mammals and has been isolated from bird feces; it is the most common pathogenic enteric clostridial organism in humans.